Respuesta :
sn=n/2[2a+(n-1)d]
s7 means n=7
a7=7/2[2(13)+(7-1)(3)]=7/2(44)=154
Ans:C
s7 means n=7
a7=7/2[2(13)+(7-1)(3)]=7/2(44)=154
Ans:C
Answer:
C. 154
Step-by-step explanation:
Here we have given that,
First Term a₁ = 13
Common Difference d = 3
Term (n ) = 7
so, we have arithmetic sequence: 13, 16, 19, 22,... and so on
Thus Sum of first 7 terms = [tex]\frac{n}{2} [2a+(n-1)d][/tex]
= 7÷2 [2*13 + (7 - 1)*3 ]
= 3.5 [ 26 + 21 ]
= 154
